It's hard to change this *system*. It's more likely blockchain will be absorbed by this mainstream system than it will reduce costs and boost economies.
We'll see. So far, we're in the early stages of Blockchain adoption among governments and central banks alike. There's still much to learn and improve in order to use Blockchain as the replacement of our entire economic system. Governments will either decide if they want to reduce costs using Blockchain technology or leave everything as is. The most likely situation will be that governments will simply launch their own digital currencies using Blockchain technology but leave the supply and everything else as it is today. They'll be the ones experiencing the benefits of Blockchain technology instead of the end-user. After all, Blockchain technology gives the government the ability to control transactions at will. It's easier for them to freeze someone's assets this way than with the traditional monetary system of today. Surveillance will be also increased over one's transactions like never before.
If by any way Blockchain technology boosts our economy in the future, it'll be a blast. But it looks very unlikely this will happen as governments will continue "printing" their own money. Supply would continue to increase over time causing inflation just like it is right now. Governments won't let their Blockchain system to be deflationary like Bitcoin, because Fiat would become extremely valuable like Gold and would serve more as a store of value than a currency for everyday transactions. In all ends, Blockchain technology has boosted our crypto economy (not the mainstream economy) in ways that we've never imagined. Just my thoughts